Coating apparatus with cooling back-up roll



Aug. 9, 1966 A. D] MINO COATING APPARATUS WITH COOLING BACK-UP ROLLFiled Oct. 31, 1963 INVENTOR. ALFO/VSO D/ M/NO United States Patent3,265,634 COATING APPARATUS WETH COULING BACK-UP ROLL Alfonso Di Mine,Woodciiif Lake, N .J., assignor to Burroughs Corporation, Detroit, Micha corporation of Michigan Filed Oct. 31, 1963, Ser. No. 326,306 2Claims. ((11. 118-68) My invention relates to the coating art and,particularly, to improved apparatus for applying decorative, protective,and useful coatings on a substrate.

The apparatus of the present invention has wide utility and may be usedto form decorative coatings, for example, such as those used onwallpaper or the like; protective coatings such as coatings of syntheticresinous material or the like, for example, for waterproofing or forother purposes; and useful coatings such as, for example, transfercoatings of the type used in carbon paper. These coatings may be formedon many different types of substrates or webs. A web is a continuoussheet of material generally of single thickness.

The prior art is replete with different types of coating apparatus.However, in general, such coating apparatus cannot successfully andeasily coat many different types, grades, and qualities of webs, such aspaper, including va-ry porous papers, with a coating of controllabledensity and thickness and with little or no readjustment of the coatingapparatus required for each type of paper coated. In addition, knownapparatus cannot be operated to provide easy control of the amount ofmaterial which is coated and the depth of penetration of the coatingmaterial into a Web, particularly a very porous web.

The speed of operation of most prior art coating apparatus is alsosubject to criticism. In general, speeds of the order of 80 feet perminute are typical in the prior art, and such speeds are undesirablylow. Furthermore, specifically considering coated articles such ascarbon paper produced by prior art apparatus, probably the most commoncriticism of such articles is that they are unpleasant to use becausethe coated material is never completely set and is readily transferredto the hands of the user.

In addition, there is no relatively simple coating apparatus availablein the prior art for applying a material which must be maintained at arelatively high temperature to a sheet or web which is itself sensitiveto such temperature or carries a coating which is temperaturesensitive.Furthermore, generally, in prior art apparatus, tension is applied tothe web as it is being coated. As a result, many Webs, for example, aweb of unsupported polyethylene, would react adversely to the tensionand could not be coated. An unsupported film of any material is a filmwhich does not have, but generally requires, a supporting substrate.

These problems in the prior art have been solved, for the most part, bythe apparatus described and claimed in my copending application SerialNo. 127,057 filed July 26, 1961. However, the apparatus of my presentinvention provides other improvements due, in part, to the fact that thepresent invention is somewhat simpler in construction and, thus, iseasier to set up, adjust, and operate. The improvements in constructionprovide many advantages which are discussed in detail below.

Accordingly, the objects of the invention are directed to the provisionof improved apparatus for coating a Web.

Briefly, the apparatus of the invention comprises a first roll which ispositioned partly submerged in a tank of coating material and which isknown as a fountain roll. A second similar roll is positioned adjacentto, but spaced from, the first roll and serves to transfer coatingmaterial to a third roll which is positioned adjacent to, but

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spaced from, the second roll and supports the web to be coated duringthe coating operation. The first, second, and third rolls are allhard-surface rolls which are fixed in position and are positivelydriven. These rolls are also spaced apart from each other.

The apparatus of the invention also includes means for transferringcoating material from the supply tank to the web to be coated by way ofthe above-mentioned rolls. This means includes a first free-floatingroll positioned between the first and second fixed rolls and adapted tobe set in frictional contact therewith whereby coating ma terial can betransferred from the fountain roll to the second roll. This means alsoincludes a second free-floating roll positioned between the second andthird fixed rolls and adapted to be brought into frictional contact withthe second roll and the web carried by the third roll whereby coatingmaterial may be transferred from the second roll to the web as a fineuniform coating. The first and second free-floating rolls have a surfaceof a soft, resilient material.

Means are also provided for regulating the temperature of the variousrolls, the arrangement being such that the supply tank of coatingmaterials, the first fountain roll, and the second fixed roll areoperated at a relatively elevated temperature to maintain the coatingmaterial in a desirably fluid state. The temperature of the thirdweb-supporting roll is adjusted to control the depth of penetration ofthe coating material into the web being coated. In general, the lowerthe temperature of the web-supporting roll and the web itself, the lessthe penetration of the coating material. One or more chill rolls mayalso be provided following the third web-supporting 'roll in the coatingcycle in order to set the coated material on the web and thus provide adry, clean coating when the web leaves the coating machine.

In operation of the coating machine of the invention, initially, thefirst and second free-floating rolls are moved into contact with thefixed rolls with which they are associated and the temperatures of thevarious rolls are adjusted as required. The first fixed fountain rollpicks up a layer of coating material on its surface from the supplytank, and some of the coating material is transferred by the first-freefloating roll to the second fixed roll. The first free-floating rollprovides a metering action in this transfer operation and form a smoothlayer of coating material on the surface of the second roll. Some ofthis coating material is now transferred, by the second free-floatingroll, directly to the surface of the web carried by the third fixedweb-supporting roll. A second metering action is preformed in thistransfer operation and a thin, smooth coating is formed on the web 'bythe second free-floating roll.

The single figure of the drawing is a side elevational view, partly insection, of coating apparatus embodying the invention.

Coating apparatus 10 embodying the invention may be i used for applyinga coating of a transfer material, such as an ink, to a paper web, andthe following description of the invention is directed toward this useof the apparatus. However, as indicated above, it will be clear to thoseskilled in the art that invention may also be used for applying manydifferent type of coating materials to many diiferent types of websother than that specifically described. In addition, the paper which maybe coated, may be of substantially any weight or quality, and it mayhave substantially any degree of porosity.

The coating apparatus 10 includes a tank or vat 12 which contains asupply of a suitable ink 1 to be coated on a paper web 16 which is fedto the apparatus from a supply reel 18. A first rotatable fountain roll20 is fixed in place horizontally with its surface partly submerged inthe coating material in the tank. A second Patented August 9, 1966rotatable .roll 24, an ink transfer roll, is horizontally mounted fixedin place parallel to, and spaced from the first fountain roll 20 and,preferably, vertically above the fountain roll. The apparatus alsoincludes a third rotatable roll 28, a web-supporting roll, which isfixed horizontally in place parallel to the other two rolls andhorizontally aligned with, and spaced from, the second coating transferroll 24. The rolls 20, 24, and 28 all have hard surfaces of stainlesssteel or the like, and they all have substantially the same diameter.

A take-up reel 29 is also provided for receiving the paper after it iscoated.

In operation of the apparatus 10, the hard-surfaced rolls 20, 24, 28 arepositively driven, and, for this purpose, they are provided with shafts30, 34, and 38, respectively, which are suitably coupled to a motor 40.The take-up reel 29 is also positively driven, for example, by couplingto motor 40. In addition, each of the rolls 20, 24, and 28 is adapted tobe operated at a controlled temperature, and the desired temperaturecontrol is most conveniently achieved by means of a fluid which iscirculated through each roll through its shaft which, of course, ishollow. Since the shafts are rotated in operation of the apparatus,suitable fluid-tight couplings 48, 50 and 54 are secured thereto topermit such rotation while allowing the flow of fluid therethrough.These couplings are connected through suitable conduits to sources ofheating or cooling fluid as required. Couplings 48 and 50, and rolls and24, are connected to a source 53 of heating fluid, and coupling 54, androlls 28, are connected to a source 55 of cooling fluid. Suitablepumping means are provided for circulating the heating and coolingfluid.

According to the invention, means are provided for transferring thecoating ink 14 from the tank 12 to the paper sheet 16 by way of thefirst and second fixed rolls 2t) and 24, and this means includes firstand second freefloating rolls 60 and 64. These rolls have a soft,resilient surface of rubber or the like, and are henceforth known asfirst and second rubber rolls. The first rubber roll 60 is horizontallymounted parallel to, and between, the first and second fixed rolls 20and 24, with its axis aligned with the horizontal center line 70 betweenthe first and second fixed rolls. The second rubber roll 64 is similarlyhorizontally mounted between, and parallel to, the second and thirdfixed rolls 24 and 28, with its axis aligned with the vertical centerline 72 between the second and third fixed rolls.

Both the first and second free-floating rubber rolls 60 and 64 aremounted on suitable frames represented schematically at 80 and 84, bywhich the rolls may be moved horizontally and vertically, respectively,into and out of contact with the fixed rolls with which each isassociated.

If desired, a plurality of chill rolls 90 and 92 are mounted adjacentto, and following, the roll 23 in the cycle of operation of theapparatus 10.

Considering the various temperatures which may be employed in operationof the apparatus 10, the temperature of the coating material in tank 14and of the rolls 20 and 24 is sumciently high to maintain the coatingmaterial in a favorably fluid state. Thus, for an ink coating of thetype used in making carbon paper, about 200 F. is suitable. The degreeof penetration of the coating material into the paper 16 is determinedby the temperature of roll 8, and the cooler the roll, the less thepenetration of the coating material. The nature of the paper is also afactor. The necessary temperatures for desired operation in each casemay be determined easily without extensive experimentation. In oneoperation of coating a carbon-paper-type ink on a typical paper, such asKraft paper, a temperature of about 140 F. was used for theweb-supporting roll 28, with the chill rolls 90 and 92 operated in therange of about 55 F. to about 65 F.

In operation of apparatus 10, the fountain roll 20, rotatingcounter-clockwise in the tank 12, as seen in FIG. 1, picks up .a layerof coating material 14 on its surface.

Roll 20, in turn, transfers coating material from its surface to thesurface of the first free-floating rubber roll 60. The roll 60 thenapplies the coating material to the surface of the roll 24 whichtransfers the coating material through rubber roll 64 to the web 16.

During this coating process, the ink is metered between each rubber rolland the two fixed rolls with which each is in contact. In addition,since the rubber rolls are freefloating, particularly roll 64, a thin,smooth, uniform coating of ink is provided on the paper sheet 16.

As described above, the degree of penetration of the coating materialinto the paper 16 is determind by the temperature differential betweenthe coating material and the paper. The temperature of the coatingmaterial is determined, essentially, by the temperature of roll 24, andthe temperature of the paper is determined by the temperature of theroll 28. The differential can be adjusted so that the coating materialwill remain substantially on the surface of the paper 16, or it maypenetrate to any desired depth within the paper. The lower temperatureof the paper also serves to set the coating preliminarily, and the finalset is achieved by chill rolls and 92. The final coating is clean anddry to the touch and is substantially smear-proof.

The present invention has many advantages. One of the most importantadvantages arises from the fact that a free-floating roll applies thecoating material directly to the web. Such a roll, not gear-driven,provides a smoother, more uniform coating than a gear-driven roll. Inaddition, with four metering surfaces provided between the first hardroll and the first rubber roll, between the first rubber roll and thesecond hard roll, between the second hard roll and the second rubberroll, and between the second rubber roll and the third hard roll, a thincoating of ink is finally provided on the web. Since there are nolarge-diameter rubber-surfaced rolls, which must betemperature-controlled, considerable expense is saved in the coatingapparatus. Such rolls are expensive and generally unable to maintaintheir temperature within close limits. In addition, since the relativelylarge metal rolls are fixed and need not be moved in operation,additional savings are made.- Finally, it is estimated that the coatingapparatus of the invention should be able to achieve, with littledifficulty, a coating speed of about 2,000 ft. per minute.

The apparatus of the invention also has the advantage that it can beused to coat at high speed a wide variety of types and qualities ofpaper from the best and heaviest papers to paper as thin as floristswrapping paper or condenser paper. In addition, because of thetemperaturecontrol arrangement, the amount and depth of penetration ofcoating material can be controlled, and, if desired, minimum amounts ofthe coating material can be used to provide a satisfactory coating.

What is claimed is:

1. A web-coating apparatus comprising a first fountain roll adapted tohave its surface partly submerged in a tank of coating material,

a second transfer roll spaced from said first fountain roll,

a third web-supporting roll spaced from said second transfer roll andsupporting a web to be coated,

said first, second, and third rolls being rotatable and positivelydriven,

a first free-floating soft-surfaced roll positioned between said firstand second fountain and transfer rolls and movable into and out ofcontact therewith,

a second free-floating soft-surfaced roll positioned between said secondand third transfer and web-supporting rolls and movable into and out ofcontact therewith,

said first and second soft-surfaced rolls being adapted to befrictionally driven by contact with their associated driven rolls,

said first fountain roll having its axis horizontally oriented,

said second transfer roll having its axis horizontally oriented andaligned vertically above the axis of said fountain roll, and

said Web-feeding roll having its axis oriented horizontally and alignedhorizontally with the axis of said transfer roll,

said first free-floating roll having its axis parallel to the axis ofthe other rolls and positioned on the center line between the axes ofsaid first and second rolls,

said second free-floating roll having its axis parallel to the axes ofthe other rolls and positioned on the center line between the axes ofsaid second and third rolls.

I References Cited by the Examiner UNITED STATES PATENTS 1,903,3254/1933 Colbert et a1 118-244 X 2,724,362 11/1955 Burke et al. 118 5593,116,166 12/ 1963 Halley 11868 CHARLES A; WILLMUTH, Primary Examiner.

LEON G. MACHLIN, Assistant Examiner.

1. A WEB-COATING APPARATUS COMPRISING A FIRST FOUNTAIN ROLL ADAPTED TOHAVE ITS SURFACE PARTLY SUBMERGED IN A TANK OF COATING MATERIAL, ASECOND TRANSFER ROLL SPACED FROM SAID FIRST FOUNTAIN ROLL, A THIRDWEB-SUPPORTING ROLL SPACED FROM SAID SECOND TRANSFER ROLL AND SUPPORTINGA WEB TO BE COATED, SAID FIRST, SECOND, AND THIRD ROLLS BEING ROTATABLEAND POSITIVELY DRIVEN, A FIRST FREE-FLOATING SOFT-FACED ROLL POSITIONEDBETWEEN SAID FIRST AND SECOND FOUNTAIN AND TRANSFER ROLLS AND MOVABLEINTO AND OUT OF CONTACT THEREWITH, A SECOND FREE-FLOATING SOFT-SURFACEDROLL POSITIONED BETWEEN SAID SECOND AND THIRD TRANSFER ANDWEB-SUPPORTING ROLLS AND MOVABLE INTO AND OUT OF CONTACT THEREWITH, SAIDFIRST AND SECOND SOFT-SURFACED ROLLS BEING ADAPTED TO BE FRICTIONALLYDRIVEN BY CONTACT WITH THEIR ASSOCIATED DRIVEN ROLLS, SAID FIRSTFOUNTAIN ROLL HAVING ITS AXIS HORIZONTALLY ORIENTED, SAID SECONDTRANSFER ROLL HAVING ITS AXIS HORIZONTALLY ORIENTED AND ALIGNEDVERTICALLY ABOVE THE AXIS OF SAID FOUNTAIN ROLL, AND SAID WEB-FEEDINGROLL HAVING ITS AXIS ORIENTED HORIZONTALLY AND ALIGNED HORIZONTALLY WITHTHE AXIS OF SAID TRANSFER ROLL, SAID FIRST FREE-FLOATING ROLL HAVING ITSAXIS PARALLEL TO THE AXIS OF THE OTHER ROLLS AND POSITIONED ON THECENTER LINE BETWEEN THE AXES OF SAID FIRST AND SECOND ROLLS, SAID SECONDFREE-FLOATING ROLL HAVING ITS AXIS PARALLEL TO THE AXES OF THE OTHERROLLS AND POSITIONED ON THE CENTER LINE BETWEEN THE AXES OF SAID SECONDAND THIRD ROLLS.